1. Field of the Invention
The present invention relates to an observation apparatus used for observing a cultured cell.
2. Description of the Related Art
In the field of biological research, various experiments have been conducted with the use of cultured cells for the study of dynamic changes in living organisms. The cultured cells are placed in a carbon dioxide incubator that is kept at an inner temperature of 37° C., a carbon dioxide gas concentration of 5%, and a humidity of 100%, together with a liquid referred to as a culture medium made from bovine serum or the like, so that the activities of the cultured cells are maintained. Moreover, observation apparatuses, which allow observation while the activities of the cultured cells are maintained with the use of a microscope equipped with functions of the carbon dioxide incubator, have been commercially available.
Cultured cells and a culture medium are generally cultured in a dish that is made of plastic or glass and has a cylindrical form in its outer shape or a petri dish which is available in various shapes. Upon observation under the microscope, the use of an appropriate holder with a suitable shape for the container is required. Otherwise, the observable area may be limited or the container may fall onto the microscope.
For this reason, Japanese Patent Application Laid-Open (JP-A) No. H11-202213 proposes a sample holder capable of holding petri dishes of various sizes and shapes with the use of a movable petri dish holder.
Some experiments using such cultured cells last a long period of time, in particular, experiments on cell lineage, in which changes in specific cells are traced, is carried out over a long period of time.
The culture medium, however, needs to be changed once approximately every three days. Hence, the long-term observation of a specific cell necessarily accompanies the exchange of culture mediums, which is carried out on a clean bench or the like after the removal of the container containing cultured cells from the microscope.
In JP-A No. H11-202213, though the petri dish can be held with the use of the shiftable petri dish holder, it is difficult to position the petri dish within a range of approximately 5 μm that is required for a high-magnification observation under a microscope.
Even if the petri dish is positioned within a range of approximately 5 μm with the use of the petri dish holder, it is impossible to position a cell located out of a center within a range of about 5 μm, because the round petri dish cannot controlled in the rotation direction.
Thus, during the long-term observation requiring the exchange of the culture medium, the specific cell practically cannot be observed immediately before and after the exchange of the culture medium.